The remarks came a day after India and China appeared willing to resolve the military standoff through dialogue.
External Affairs Minister Sushma Swaraj told the Rajya Sabha that India was willing to talk to China on the standoff in Sikkim sector, "but both sides have to first take back their armies." She said the boundaries between the countries are not yet finalised and it will be done bilaterally through discussions.
"This is a situation that we are following closely and carefully," State Department spokeswoman Heather Nauert said.
"I'd have to refer you to the governments of India and China for more information on that," she told reporters and added that Indian and China were talking on the issue.
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Referring to the visit of India's National Security Adviser Ajit K Doval to Beijing for a meeting of the NSAs from BRICS countries on July 27-28, Nauert said: "They're going to talk to one another."
Chinese and Indian soldiers have been locked in a face- off in Doklam area in the southernmost part of Tibet for over a month after Indian troops stopped the Chinese army from building a road, fearing it may allow China to cut India's access to its northeastern states.
India has conveyed to China that the construction of the road would represent a significant change of status quo with serious security implications for New Delhi.
India and China share a 220-km-long border in Sikkim.